Positive-working photoresist composition

Abstract: The present invention provides a positive-working photoresist composition comprising an alkali-soluble resin and a 1,2-naphthoquinonediazide-5-(and/or -4-)sulfonic ester of a specific water-insoluble alkali-soluble low molecular compound, wherein the high-performance liquid chromatography of the ester with an ultraviolet ray at 254 nm shows that the patterns corresponding to the diester components and complete ester component of the ester each fall within the specific range and a positive-working photoresist composition comprising a water-insoluble alkali-soluble resin, a water-insoluble alkali-soluble low molecular compound, and an ionization-sensitive radioactive compound which comprises a mixture of a naphthoquinone-diazidesulfonic diester of a water-insoluble alkali-soluble low molecular compound having three phenolic hydroxyl groups as an ionization-sensitive radioactive compound (A) and a naphthoquinonediazidesulfonic diester of a water-insoluble alkali-soluble low molecular compound having four phenolic hydroxyl groups as an ionization-sensitive radioactive compound (B) in an amount of 30 % or more by weight based on the total amount of the ionization-sensitive radioactive compound.

Description: FIELD OF THE INVENTION The present invention relates to a positive-working photoresist composition comprising an alkali-soluble resin and a specific 1,2-quinonediazide compound which is sensitive to radiations such as ultraviolet ray, far ultraviolet ray, X ray, electron ray, molecular beam, γ-ray and synchrotron radiation. More particularly, the present invention relates to a positive-working photoresist for fine work which provides a high resolving power against the fluctuations in the film thickness, gives little development residue and exhibits an excellent development latitude and a high age stability. The positive-working photoresist of the present invention is generally applied to a substrate such as semiconductor wafer, glass, ceramics and metal to a thickness of 0.5 to 2 µm by spin coating method or roller coating method. Thereafter, the material is heated to dryness, irradiated with an ultraviolet ray etc. through an exposure mask to print a circuit pattern thereon, and then developed, optionally after baking, to form a positive image thereon. With this positive image as a mask, the substrate is then etched to effect patternwise work thereon. This technique finds typical applications in the production of semiconductors such as IC, the production of circuit boards such as a liquid crystal and thermal head, the production of a magnetic bubble memory device, and other photofabrication processes, etc. BACKGROUND OF THE INVENTION As a positive-working photoresist composition there is normally used a composition comprising an alkali-soluble resin binder such as novolak and a naphthoquinonediazide compound as a photosensitive material. A novolak resin which serves as a binder can be dissolved in an alkaline aqueous solution without swelling. The novolak resin can also exhibit a high resistance particularly to plasma etching when an image thus produced is used as a mask for etching. Thus, novolak resin is particularly useful in this application. A naphthoquinone diazide compound which serves as a photosensitive material itself serves as a dissolution inhibitor for reducing the alkali solubility of novolak resin but is peculiar in that it undergoes decomposition upon the irradiation with light to produce an alkali-soluble substance which rather enhances the alkali solubility of novolak resin. Because of the great change in properties by the irradiation with light, naphthoquinone diazide compound is particularly useful as photosensitive material for positive-working photoresist. From such a standpoint of view, many positive-working photoresists comprising novolak resin and naphthoquinone photosensitive material have heretofore been developed and put into practical use. These positive-working photoresist materials have showed marked progress particularly towards high resolving power and attained sufficient results in working lines having a width as small as submicron. It has heretofore been considered that a resist having a high contrast (γ value) can be advantageously used to provide reproduction of a faithfully-patterned image with an enhanced resolving power. In an attempt to accomplish the foregoing object, various resist compositions have been developed. An extremely large number of publications disclose this technique. Referring particularly to novolak resin as a main component of positive-working photoresist, many monomer compositions, molecular weight distributions, synthesis methods, etc. have been applied for patent. These patents have attained some good results. An attempt to improve the properties of resists by providing a novolak resin with a specified molecular weight distribution is known. For example, JP-A-1-105243 (The term "JP-A" as used herein means an "unexamined published Japanese patent application") discloses that a novolak resin having a molecular weight distribution such that the molecular weight range of 500 to 5,000 accounts for not more than 30 % of the molecular weight distribution is desirable. Further, JP-A-62-227144 and JP-A-63-2044 disclose that there is a desirable proportion of specified molecular weight ranges in the molecular weight distribution. Moreover, JP-A-60-97347 and JP-A-60-189739 disclose the use of a novolak resin from which a low molecular weight component has been fractionally removed. Also, JP-A-60-45238 disclose the use of a resin having a dispersion degree of not more than 3 as used herein. Referring to photosensitive material as another main component of positive-working photoresist, many compounds structured so as to provide a high contrast have been disclosed. The design of positive-working photoresist taking advantage of these techniques makes it possible to develop a ultrahigh resolving resist that can resolve a pattern with the same dimension as the wavelength of light. However, integrated circuits have developed its degree of integration more and more. In the production of semiconductor substrates such as SLSI (super large scale integration), the working of ultrafine patterns composed of lines having a width down to not more than 0.5 µm has been required. Such an application has required a photoresist having a development latitude wide enough to provide an invariably high resolving power and keep the width of worked lines constant. In order to prevent circuits from being malworked, it is necessary that no resist residues occur on the resist pattern developed. Further, a low molecular compound having aromatic hydroxyl group is normally used as a dissolution accelerator or for the purpose of enhancing sensitivity. Many cases of the addition of such a low molecular compound have been disclosed. However, the addition of such a compound normally causes a rise in the reduction of the thickness of unexposed area, resulting in the deterioration of the shape of the resist. In addition, the addition of such a compound increases the development speed and hence reduces the development latitude. Thus, the structure of desirable compounds have been selected such that these phenomena can be minimized. An attempt to improve the sensitivity and developability of resists by blending a specific compound in the resist compositions has been made. For example, JP-A-61-141441 discloses a positive-working photoresist composition containing trihydroxybenzophenone. The positive-working photoresist composition containing trihydroxybenzophenone can exhibit an improved sensitivity and developability but is disadvantageous in that the presence of trihydroxybenzophenone causes a deterioration of the heat resistance that results in the rise in the reduction of the film thickness of unexposed area. It has also been found that the formation of an ultrafine pattern having a line width as small as not more than 0.5 µm is liable to a phenomenon in which, although a specified resolving power can be obtained with a predetermined coat film thickness, even a slight change in the coat film thickness can deteriorate the resolving power (hereinafter referred to as "dependence on film thickness"). A surprising fact has also been found that even a change in the film thickness as small as few hundredths of micron can cause a great change in the resolving power and any commercially available typical positive-working photoresists show such a behavior more or less. In some detail, when the thickness of the resist film which has not been exposed changes in a proportion of λ/4n (in which λ is the wavelength of light to which the resist is exposed, and n is the refractive index of the resist film at the same wavelength), the resulting resolving power can vary. Referring to the problem of dependence on film thickness, its presence is noted in, e.g., SPIE Proceedings, vol. 1,925, page 626, 1993. The paper reports that this phenomenon can be caused by a multiple light reflection effect in the resist film. It has been found that this dependence on film thickness becomes remarkable particularly when the contrast of the resist is raised such that a high resolving power and a pattern having a rectangular section can be obtained. In the actual work of semiconductor substrates, a pattern is formed using a resist film having slight fluctuation in film thickness due to roughness on the surface of the substrate or unevenness in the coat film thickness. Thus, this dependence on film thickness is one of obstacles to the work of ultrafine patterns close to the limit of resolution with a positive-working photoreist. Many 1,2-naphthoquinonediazidization products of polyhydroxy compound having a specific structure have heretofore been proposed to enhance the resolving power. These compounds are disclosed in JP-A-57-63526, JP-A-60-163043, JP-A-62-10645, JP-A-62-10646, JP-A-62-150245, JP-A-63-220139, JP-A-64-76047, JP-A-1-189644, JP-A-2-285351, JP-A-2-296248, JP-A-2-296249, JP-A-3-48249, JP-A-3-48250, JP-A-3-158856, JP-A-3-228057, JP-A-4-502519, U.S. Patents 4,957,846, 4,992,356, 5,151,340, and 5,178,986, and EP 530,148. However, even these photosensitive materials leave something to be desired in the reduction of dependence on film thickness. On the other hand, it is disclosed in JP-B-37-18015 (The term "JP-B" as used herein means an "examined Japanese patent publication"), JP-A-58-150948, JP-A-2-19846, JP-A-2-103543, JP-A-3-228057, JP-A-5-323597, EP 573,056, U.S. Patents 3,061,430, 3,130,047, 3,130,048, 3,130,049, 3,102,809, 3,184,310, 3,188,210, and 3,180,733, West German Patent 938,233, and SPIE Proceedings, vol. 631, page 210, vol. 1,672, page 231 (1992), vol. 1,672, page 262 (1992) and vol. 1,925, page 227 (1993) that the use of a photosensitive material having hydroxyl group in its molecule can provide a resist having a high contrast and a high resolving power. Selectively esterified photosensitive materials each having three aromatic rings (formulae (III) to (V)) are proposed in SPIE Proceedings, vol. 1,672, pp. 262 - 272. wherein D represents 1,2-naphthoquinonediazide-5-(and/or -4-) sulfonyl group. However, these photosensitive materials leave something to be desired in the reduction of dependence on film thickness, though providing a sufficiently enhanced resolving power. Further, JP-A-2-19846 and JP-A-2-103543 disclose diesterification products of polyhydroxy compound having, e.g., the following specific structural formulae (VI) to (VIII). As a result of the examination of these diester photosensitive materials for dependence on film thickness, it was found that these photosensitive materials, too, leave something to be desired. Moreover, 1,2-naphthoquinonediazide-5-(and/or -4-) sulfonyl chlorides of compounds having the following structural formulae (IX) and (X) disclosed in U.S. Patent 5,178,986, JP-A-57-63526, and JP-A-62-10646 leave something to be desired in the reduction of dependence on film thickness. wherein R 16b to R 18b , R 23b , R 24b , R 26b , and R 28b , may be the same or different and each represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryl group or a nitro group; and R 19b to R 22b R 25b , R 27b , and R 29b , each represent a hydrogen atom or an alkyl group. It has heretofore been quite unknown how the composition of resist materials should be formulated to reduce the dependence on film thickness, making it possible to provide a high resolving power independent of film thickness. With the recent rise in the integration of semiconductor circuits, the demand for the elimination of particles produced from positive-working photoresists has grown more and more. In the field of semiconductor circuits, as the so-called "1/10 rule" says, particles having a size of not less than 1/10 of the smallest line width of device affect the yield of semiconductor circuits (see "Ultraclean Technology", vol. 3, No. 1, page 79 (1991)). In order to eliminate these particles, some schemes such as use of a filter having a pore diameter as small as 0.1 µm or 0.05 µm have been made. These schemes can help eliminate particles during the preparation of resists. However, even if there are few particles during the preparation of resists, particles can often occur more and more with time. The occurrence of particles with time is mostly attributed to 1,2-quinonediazide photosensitive materials. In order to improve the age stability of resists, various schemes have been made. For example, the use of a photosensitive material in which the hydroxyl groups in polyhydroxy compound is partially acylated or sulfonylated (JP-A-62-178562), the use of a mixture of 1,2-naphthoquinonediazide-4-sulfonic ester and 1,2-naphthoquinonediazide-5-sulfonic ester (JP-A-62-284354), the use of a thermally modified 1,2-naphthoquinonediazide photosensitive material (JP-A-63-113451), the reduction of residual catalyst in photosensitive material (JP-A-63-236030), the synthesis of a photosensitive material in the presence of an anion exchange resin (JP-A-63-236031), the mixing of a photosensitive material with a solution having a high power of dissolving the photosensitive material (JP-A-61-260239, JP-A-1-293340), etc. have been heretofore attempted. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a positive-working photoresist composition for fine work which exhibits a high resolving power and a small dependence of resolving power on film thickness. The term "dependence on film thickness" as used herein is meant to indicate the variation in the resolving power of the resist obtained by the exposure (optionally followed by baking) and development of the positive-working photoresist composition with the change of the resist thickness within the range of λ/4n before exposure. It is another object of the present invention to provide a positive-working photoresist composition which exhibits a wide development latitude and gives little development residue. The term "development latitude" as used herein can be represented by the dependence of the width of the resist obtained by development on the development time or the temperature dependence of the developer. The term "development residue" as used herein is meant to indicate a slight amount of resist insolubles left between developed fine pattern lines which can be observed under a scanning electron microscope. It is a further object of the present invention to provide a positive-working photoresist composition which is free from deposition of a photosensitive agent and production of microgel with time, i.e., shows no rise in the number of particles with time, to attain an extremely excellent storage stability. These and other objects of the present invention will become more apparent from the following detailed description and examples. The inventors made extensive studies taking the foregoing properties into consideration. As a result, it has been found that the foregoing problems can be solved by the use of an alkali-soluble resin and a quinonediazide compound having a specific mother nucleus wherein the ratio of intramolecular hydroxyl group to 1,2-quinonediazide-5-(and/or -4-)sulfonic ester group is in a specified range. The present invention has been worked out on the basis of this knowledge. The foregoing objects of the present invention are accomplished with the present invention. The present invention provides a positive-working photoresist composition, comprising an alkali-soluble resin and a 1,2-naphthoquinonediazide-5-(and/or -4-)sulfonic ester of a water-insoluble alkali-soluble low molecular compound represented by formula (Ib) obtained by the esterification reaction of a water-insoluble alkali-soluble low molecular compound represented by formula (Ib) with 1,2-naphthoquinonediazide-5-(and/or 4-)sulfonyl chloride, wherein the high-performance liquid chromatography of said ester with an ultraviolet ray at 254 nm shows that the patterns corresponding to the diester component and complete ester component of said ester account for not less than 40 % and less than 10 % of the total pattern area of said ester, respectively: wherein R 1b to R 10b may be the same or different and each represents a hydrogen atom, a halogen atom selected from a chlorine atom, a bromine atom and an iodine atom, a C 1-4 alkyl group, a cyclic alkyl group selected from a cyclopentyl group and a cyclohexyl group, an aryl group selected from a phenyl group, a toluyl group, a xylyl group and a cumenyl group, a C 1-4 alkoxy group, an acyl group selected from a formyl group, an acetyl group and a benzoyl group, an alkenyl group selected from a vinyl group, a propenyl group and an allyl group, or a hydroxyl group, with the proviso that at least one of R 1b to R 5b and at least one of R 6b to R 10b each is a hydroxyl group; and R 11b to R 14b may be the same or different and each represent a hydrogen atom or an C 1-4 alkyl group. The present invention will be further described hereinafter. It is unknown why the use of the photosensitive material of the present invention can provide a uniquely high resolving power, little dependence on film thickness, a wide development latitude and an extremely excellent storage stability and hardly cause the production of development residue. It is possibly because that these unique effects are exerted by the structural features: (1) straight-chain, (2) skeleton having four aromatic rings, (3) compound having one hydroxyl group in each aromatic ring, and (4) hydroxyl groups at both ends can be selectively esterified, and (5) cycloalkyl groups are present in the molecule. In addition, among the structural features, the presence of cycloalkyl group can probably enhance the storage stability. For example, a C 1-6 straight-chain or branched alkyl group or an aryl groups such as a phenyl group leave something to be desired in storage stability. In other words, it has been found that the features (1) to (4) are effective for the improvement of resolving power and dependence on film thickness while the feature (5) is effective particularly for the improvement of storage stability. This was unexpected from the conventional knowledge. Preferred examples of the alkyl group represented by R 1b to R 10b and R 11b to R 14b in the foregoing formula (Ib) include a C 1-4 alkyl group such as methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group and tert-butyl group. Particularly preferred among these alkyl groups is a methyl group. The group represented by R 11b to R 14b is preferably a hydrogen atom. Preferred examples of the C 1-4 alkoxy group represented by R 1b to R 10b include methoxy group, ethoxy group, propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, sec-butoxy group and t-butoxy group. Specific examples of the compound represented by formula (Ib) include those represented by formulae (Ib-1) to (Ib-12), but the present invention should not be construed as being limited thereto. These water-insoluble alkali-soluble low molecular compounds may be used singly or in combination. Among these compounds, Compounds (Ib-1), (Ib-2) and (Ib-3) can exert the best effect of accomplishing the objects of the present invention. The photosensitive material of the present invention can be obtained by the esterification reaction of e.g., the foregoing water-insoluble alkali-soluble low molecular compound with 1,2-naphthoquinonediazide-5-(and/or -4-)sulfonyl chloride in the presence of a basic catalyst. In some detail, a predetermined amount of such a water-insoluble alkali-soluble low molecular compound and a solvent such as 1,2-naphthoquinonediazide-5-(and/or -4-)sulfonyl chloride, acetone, methyl ethyl ketone, methyl isobutyl ketone, 1,4-dioxane, tetrahydrofuran, dimethoxyethane, diglyme, ethyl acetate, acetonitrile, chloroform, dichloromethane, dichloroethane, chlorobenzene, N-methylpyrrolidone and γ-butyl lactone are charged into a flask. A basic catalyst such as sodium hydroxide, sodium carbonate, sodium hydrogencarbonate, triethylamine, N-methylmorpholine, N-methylpiperidine, N-methylpyrrolidine and 1,4-dimethylpiperazine is then added dropwise to the mixture to effect condensation. The resulting product is crystallized from water, washed with water, purified, and then dried. In the ordinary esterification reaction, mixtures having different esterification degrees and esterification positions are obtained. The use of the water-insoluble alkali-soluble low molecular compound of the present invention makes it possible to effect the selective esterification of diester compounds. However, it is necessary that the content of diester compounds and the content of complete ester compounds be controlled to not less than 40 % and less than 10 %, respectively, as calculated in terms of area ratio determined by high performance liquid chromatography. If the content of diester compounds falls below 40 % and the content of complete ester compounds exceed 10 %, the dependence on film thickness is increased, making it impossible to exert the effects of the present invention. Preferably, the content of diester compound is not less than 50 %, and the content of complete ester compounds is less than 6 %. More preferably, the content of diester compound is not less than 60 %, and the content of complete ester compounds is less than 6 %. In order to further enhance the selectivity of the esterification reaction, 1,4-dioxane, tetrahydrofuran, dimethoxyethane, diglyme, ethyl acetate, chloroform, dichloromethane, dichloroethane and chlorobenzene are preferably used among the foregoing solvents. Preferred among the foregoing basic catalysts are N-methylmorpholine, N-methylpiperidine, N-methylpyrrolidine and 1,4-dimethylpiperazine. Particularly preferred among these basic catalysts are N-methylpiperidine and N-methylpyrrolidine. If necessary, 1,2-naphthoquinonediazide-5-sulfonic ester and 1,2-naphthoquinonediazide-4-sulfonic ester may be used in combination. The temperature at which the foregoing reaction occurs is normally in the range of - 20 °C to 60 °C, preferably 0 °C to 40 °C. One or more of the photosensitive compounds used according to the present invention may be used singly or in combination in the form of a blend with an alkali-soluble resin. The amount of the photosensitive compounds to be added is in the range of 5 to 100 parts by weight, preferably 20 to 60 parts by weight based on 100 parts by weight of the alkali-soluble resin. If the amount falls below 5 parts by weight, the percent film retention is remakably reduced. On the contrary, if the amount exceeds 100 parts by weight, the sensitivity and the solubility in the solvent are reduced. Examples of the alkali-soluble resin employable in the present invention include a novolak resin, an acetone-pyrogallol resin, polyhydroxystyrene, and derivatives thereof. Particularly preferred among these alkali-soluble resins is a novolak resin. The novolak resin can be obtained by addition condensation of an aldehyde with a predetermined monomer as a main component in the presence of an acidic catalyst. Examples of such a predetermined monomer include cresols such as phenol, m-cresol, p-cresol and o-cresol, xylenols such as 2,5-xylenol, 3,5-xylenol, 3,4-xylenol and 2,3-xylenol, alkylphenols such as m-ethylphenol, p-ethylphenol, o-ethylphenol and p-t-butylphenol, trialkylphenols such as 2,3,5-trimethylphenol and 2,3,4-trimethylphenol, alkoxyphenols such as p-methoxyphenol, m-methoxyphenol, 3,5-dimethoxyphenol, 2-methoxy-4-methylphenol, m-ethoxyphenol, p-ethoxyphenol, m-propoxyphenol, p-propoxyphenol, m-butoxyphenol and p-butoxyphenol, bisalkylphenols such as 2-methyl-4-isopropylphenol, and hydroxyaromatic compounds such as m-chlorophenol, p-chlorophenol, o-chlorophenol, dihydroxybiphenyl, bisphenol A, phenylphenol, resorcinol and naphthol. These monomers may be used singly or in combination. The present invention should not be limited to these monomers. Examples of aldehydes to be used include formaldehyde, paraformaldehyde, acetaldehyde, propylaldehyde, benzaldehyde, phenylacetaldehyde, α-phenylpropylaldehyde, β-phenylpropylaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, o-chlorobenzoaldehyde, m-chlorobenzaldehyde, p-chlorobenzaldehyde, o-nitrobenzaldehyde, m-nitrobenzaldehyde, p-nitrobenzaldehyde, o-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde, p-ethylbenzaldehyde, p-n-butylbenzaldehyde, furfural, chloroacetaldehyde, and acetal compounds thereof, e.g., chloroacetaldehyde diethyl acetal. Preferred among these aldehydes is formaldehyde. These aldehydes may be used singly or in combination. As acidic catalysts there can be used hydrochloric acid, sulfuric acid, formic acid, acetic acid, and oxalic acid. Techniques as disclosed in JP-A-60-45238, JP-A-60-97347, JP-A-60-140235, JP-A-60-189739, JP-A-64-14229, JP-A-1-276131, JP-A-2-60915, JP-A-2-275955, JP-A-2-282745, JP-A-4-101147, and JP-A-4-122938 may be employed. In some detail, novolak resins free of or having a reduced amount of a low molecular component are preferably used. The weight-average molecular weight of the novolak resin thus obtained is preferably in the range of 1,000 to 20,000. If this value falls below 1,000, the reduction in the film on the unexposed portion after development is increased. On the contrary, if this value exceeds 20,000, the development speed is reduced. The particularly preferred range of the weight-average molecular weight of the novolak resin is from 2,000 to 15,000. The weight-average molecular weight of the novolak resin is defined by gel permeation chromatography as calculated in terms of polystyrene. The degree of dispersion (ratio of the weight-average molecular weight Mw/the number-average molecular weight Mn, i.e., Mw/Mn) of the novolak resin is preferably in the range of 1.5 to 5.0, more preferably 1.5 to 4.0. If Mw/Mn exceeds 7, the effect of the present invention of keeping little dependence on film thickness cannot be attained. On the other hand, if Mw/Mn falls below 1.5, the synthesis of the novolak resin requires a high precision purification procedure which cannot be put into practical use. In the present invention, the foregoing photosensitive material should be used. If necessary, the product of the esterification reaction of the following water-insoluble alkali-soluble low molecular compound with 1,2-naphthoquinonediazide-5-(and/or -4-)sulfonyl chloride may be used in combination with the foregoing photosensitive material. The weight ratio of the naphthoquinonediazide esterification product of the water-insoluble alkali-soluble low molecular compound as photosensitive material to the photosensitive material of the present invention is preferably in the range of 20/80 to 80/20 in the first and second aspects of the present invention. In other words, if the proportion of the photosensitive material in all the photosensitive materials falls below 20 % by weight, the effects of the present invention cannot be thoroughly exerted. Examples of such a water-insoluble alkali-soluble low molecular compound include polyhydroxybenzophenones such as 2,3,4-trihydroxybenzophenone, 2,4,4'-trihydroxybenzophenone, 2,4,6-trihydroxybenzophenone, 2,3,4-trihydroxy-2'-methylbenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,4,6,3',4'-pentahydroxybenzophenone, 2,3,4,2',4'-pentahydroxybenzophenone, 2,3,4,2',5'-pentahydroxybenzophenone, 2,4,6,3',4',5'-hexahydroxybenzophenone and 2,3,4,3',4',5'-hexahydroxybenzophenone, polyhydroxyphenylalkylketones such as 2,3,4-trihydroxyacetophenone, 2,3,4-trihydroxyphenylpenthylketone and 2,3,4-trihydroxyphenylhexylketone, bis((poly)hydroxyphenyl)alkanes such as bis(2,4-dihydroxyphenyl)methane, bis(2,3,4-trihydroxyphenyl)methane, bis(2,4-dihydroxyphenyl)propane-1, bis(2,3,4-trihydroxyphenyl)propane-1 and nordihydroguaiaretic acid, ester polyhydroxybenzoates such as propyl 3,4,5-trihydroxybenzoate, phenyl 2,3,4-trihydroxybenzoate and phenyl 3,4,5-trihydroxybenzoate, bis(polyhydroxybenzoyl) alkanes or bis(polyhydroxybenzoyl)aryls such as bis(2,3,4-trihydroxybenzoyl)methane, bis(3-acetyl-4,5,6-trihydroxyphenyl)methane, bis(2,3,4-trihydroxybenzoyl)benzene and bis(2,4,6-trihydroxybenzoyl)benzene, alkylene di(polyhydroxybenzoate)'s such as ethylene glycol di(3,5-dihydroxybenzoate) and ethylene glycol di(3,4,5-trihydroxybenzoate), polyhydroxybiphenyls such as 2,3,4-biphenyltriol, 3,4,5-biphenyltriol, 3,5,3',5'-biphenyltetrol, 2,4,2',4'-biphenyltetrol, 2,4,6,3',5'-biphenylpentol, 2,4,6,2',4',6'-biphenylhexol and 2,3,4,2',3',4'-biphenylhexol, bis(polyhydroxy)sulfides such as 4,4'-thiobis(1,3-dihydroxy)benzene, bis(polyhydroxyphenyl)ethers such as 2,2',4,4'-tetrahydroxydiphenylether, bis(polyhydroxyphenyl)sulfoxides such as 2,2',4,4'-tetrahydroxydiphenyl sulfoxide, bis(polyhydoxyphenyl)sulfones such as 2,2',4,4'-diphenylsulfone, polyhydroxytriphenylmethanes such as tris(4-hydroxyphenyl)methane, 4,4',4''-trihydroxy-3,5,3',5'-tetramethyltriphenylmethane, 4,4',3'',4''-tetrahydroxy-3,5,3',5'-tetramethyltriphenylmethane, 4,4',2'',3'',4''-pentahydroxy-3,5,3',5'-tetramethyltriphenylmethane, 2,3,4,2',3',4'-hexahydroxy-5,5'-diacetyltriphenylmethane, 2,3,4,2',3',4',3'',4''-octahydroxy-5,5'-diacetyltriphenylmethane and 2,4,6,2',4',6'-hexahydroxy-5,5'-dipropionyltriphenylmethane, polyhydroxyspirobi-indanes such as 3,3,3',3'-tetramethyl-1,1'-spirobi-indane-5,6,5',6'-tetrol, 3,3,3',3'-tetramethyl-1,1'spriobi-indane-5,6,7,5',6',7'-hexol, 3,3,3',3'-tetramethyl-1,1'-spirobi-indane-4,5,6,4',5',6'-hexol and 3,3,3',3'-tetramethyl-1,1'-spirobi-indane-4,5,6,5',6',7'-hexol, polyhydroxy phthalides such as 3,3-bis(3,4-dihydroxyphenyl)phthalide, 3,3-bis(2,3,4-trihydroxyphenyl)phthalide and 3',4',5',6'-tetrahydroxyspiro [phthalide-3,9'-xanthene], flavono dyes such as morin, quercetin and rutin, polyhydroxy compounds described in JP-A-4-253058 such as α,α',α''-tris(4-hydroxyphenyl)-1,3,5-triisopropylbenzene, α,α',α''-tris(3,5-dimethyl-4-hydroxyphenyl)-1,3,5-triisopropylbenzene, α,α',α''-tris(3,5-diethyl-4-hydroxyphenyl)-1,3,5-triisopropylbenzenne, α,α',α''-tris(3,5-di-n-propyl-4-hydroxyphenyl)-1,3,5-triisopropylbenzene, α,α',α''-tris(3,5-diisopropyl-4-hydroxyphenyl)-1,3,5-triisopropylbenzene,α,α',α''-tris(3,5-di-n-butyl-4-hydroxyphenyl)-1,3,5-triisopropylbenzene, α,α',α''-tris(3-methyl-4-hydroxyphenyl)-1,3,5-triisopropylbenzene, α,α',α''-tris(3-methoxy-4-hydroxyphenyl)-1,3,5-trisopropylbenzene, α,α',α''-tris(2,4-dihydroxyphenyl)-1,3,5-triisopropylbenzene, 1,3,5-tris(3,5-dimethyl-4-hydroxyphenyl)benzene, 1,3,5-tris(5-methyl-2-hydroxyphenyl)benzene, 2,4,6-tris(3,5-dimethyl-4-hydroxyphenylthiomethyl)mesitylene, 1-[α-methyl-α-(4'-hydroxyphenyl)ethyl]-4-[α,α'-bis(4''-hydroxyphenyl) ethyl]benzene, 1-[α-methyl-α-(4'-hydroxyphenyl)ethyl]-3-[α,α'-bis(4''-hydroxyphenyl)ethyl]benzene, 1-[α-methyl-α-(3',5'-dimethyl-4'-hydroxyphenyl)ethyl]-4-[α,α'-bis(3'',5''-dimethyl-4''-hydroxyphenyl)ethyl]benzene, 1-[α-methyl-α-(3'-methyl-4'-hydroxyphenyl)ethyl]-4-[α,α'-bis(3''-methyl-4''-hydroxyphenyl)ethyl]benzene, 1-[α-methyl-α-(3'-methoxy-4'-hydroxyphenyl)ethyl]-4-[α,α'-bis(3''-methoxy-4''-hydroxyphenyl)ethyl]benzene, 1-[α-methyl-α-(2',4'-dihydroxyphenyl)ethyl]-4-[α,α'-bis(4''-hydroxyphenyl)ethyl] benzene and 1-[α-methyl-α-(2',4'-dihydroxyphenyl)ethyl]-3-[α'',α'-bis(4''-hydroxyphenyl)ethyl]benzene, p-bis(2,3,4-trihydroxybenzoyl)benzene, p-bis(2,4,6-trihydroxybenzoyl) benzene, m-bis(2,3,4-trihydroxybenzoyl)benzene, m-bis(2,4,6-trihydroxybenzoyl)benzene, p-bis(2,5-dihydroxy-3-bromobenzoyl)benzene, p-bis(2,3,4-trihydroxy-5-methylbenzoyl) benzene, p-bis(2,3,4-trihydroxy-5-methoxybenzoyl)benzene, p-bis(2,3,4-trihydroxy-5-nitrobenzoyl)benzene, p-bis(2,3,4-trihydroxy-5-cyanobenzoyl)benzene, 1,3,5-tris(2,5-dihydroxybenzoyl)benzene, 1,3,5-tris(2,3,4-trihydroxybenzoyl)benzene, 1,2,3-tris(2,3,4-trihydroxybenzoyl)benzene, 1,2,4-tris(2,3,4-trihydroxybenzoyl)benzene, 1,2,4,5-tetrakis(2,3,4-trihydroxybenzoyl)benzene, α,α'-bis(2,3,4-trihydroxybenzoyl)-p-xylene, α,α',α''-tris(2,3,4-trihydroxybenzoyl)mesitylene, 2,6-bis-(2'-hydroxy-3',5'-dimethyl-benzyl)-p-cresol, 2,6-bis-(2'-hydroxy-5'methyl-benzyl)-p-cresol,2,6-bis-(2'-hydroxy-3',5'-di-t-butyl-benzyl)-p-cresol, 2,6-bis-(2'-hydroxy-5'-ethylbenzyl)-p-cresol, 2,6-bis-(2',4'-dihydroxy-benzyl)-p-cresol, 2,6-bis-(2'-hydroxy-3'-t-butyl-5'-methyl-benzyl)-p-cresol, 2,6-bis-(2',3',4'-trihydroxy-5'-acetyl-benzyl)-p-cresol, 2,6-bis-(2',4',6'-trihydroxy-benzyl)-p-cresol, 2,6-bis-(2',3',4'-trihydroxy-benzyl)-p-cresol, 2,6-bis-(2',3',4'-trihydroxy-benzyl)-3,5-dimethyl-phenol, 4,6-bis-(4'-hydroxy-3',5'-dimethyl-benzyl)-pyrogallol, 4,6-bis-(4'-hydroxy-3',5'-dimethoxy-benzyl)-pyrogallol, 2,6-bis-(4'-hydroxy-3',5'-dimethyl-benzyl)-1,3,4-trihydroxy-phenol, 4,6-bis-(2',4',6'-trihydroxy-benzyl)-2,4-dimethyl-phenol, and 4,6-bis-(2',3',4'-trihydroxy-benzyl)-2,5-dimethyl-phenol. Further, lower nucleus compounds of phenol resin such as novolak resin can be used. The composition of the present invention may further comprise other water-insoluble alkali-soluble low molecular compounds to accelerate its solubility in the developer. Preferred examples of such water-insoluble alkali-soluble low molecular compounds include phenols, resorcin, phloroglucin, 2,3,4-trihydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, 2,3,4,3',4',5'-hexahydroxybenzophenone, acetone-pyrogallol condensation resin, phloroglucide, 2,4,2',4'-biphenyltetrol, 4,4'-thiobis(1,3-dihydroxy)benzene, 2,2',4,4'-tetrahydroxydiphenylether, 2,2',4,4'-tetrahydroxydiphenylsulfoxide, 2,2',4,4'-tetrahydroxydiphenylsulfone, tris(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 4,4'-(α-methylbenzylidene)bisphenol, α,α',α''-tris(4-hydroxyphenyl)-1,3,5-triisopropylbenzene, α,α',α''-tris(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene, 1,2,2-tris(hydroxyphenyl)propane, 1,1,2-tris(3,5-dimethyl-4-hydroxyphenyl)propane, 2,2,5,5-tetrakis(4-hydroxyphenyl)hexane, 1,2-tetrakis(4-hydroxphenyl)ethane, 1,1,3-tris(hydroxyphenyl)butane, and para[α,α,α',α'-tetrakis(4-hydroxyphenyl)]-xylene. In the present invention, these water-insoluble alkali-soluble low molecular compounds may be added normally in an amount of not more than 100 parts by weight, preferably 5 to 50 parts by weight based on 100 parts by weight of all the quinonediazide compounds. Examples of solvent for dissolving the photosensitive material and alkali-soluble novolak resin of the present invention therein include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol methyl ether acetate, propylene glycol propyl ether acetate, toluene, xylene, methyl ethyl ketone, cyclohexanone, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutanate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethyl acetate, and butyl acetate. These organic solvents may be used singly or in combination. Further, high boiling solvents such as N-methylformamide, N,N-dimethylformamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide and benzyl ethyl ether may be used in admixture. The positive-working photoresist composition of the present invention may comprise a surface active agent incorporated therein to further enhance coating properties such as anti-striation properties. Examples of such a surface active agent include nonionic surface active agents such as polyoxyethylene alkyl ethers (e.g., polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether), polyoxyethylene alkyl allyl ethers (e.g., polyoxyethylene octyl phenol ether, polyoxyethylene nonyl phenol ether), polyoxyethylene-polyoxypropylene block copolymers, sorbitan aliphatic esters (e.g., sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitan tristearate) and polyoxyethylene sorbitan aliphatic esters (e.g., polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tristearate), fluorine surface active agents such as F Top EF301, EF303 and EF352 (produced by Shinakita Kasei K.K.), Megafac F171, F173 (produced by Dainippon Ink And Chemicals, Incorporated), Florad FC430, FC431 (produced by Sumitomo 3M), and Asahi Guard AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105, SC106 (Asahi Glass Company, Limited), Organosiloxane polymer KP341 (produced by The Shin-etsu Chemical Industry Co., Ltd.), and acrylic or methacrylic (co)polymer Polyflow Nos. 75 and 95 (produced by Kyoeisha Yushi kagaku Kogyo K.K.). Particularly preferred among these surface active agents are fluorine surface active agents and silicone surface active agents. The amount of such a surface active agent to be blended in the system is normally in the range of not more than 2 parts by weight, preferably not more than 1 part by weight based on 100 parts by weight of the total amount of the alkali-soluble resin and the quinonediazide compound in the composition of the present invention. These surface active agents can be added to the system singly or in combination. As a developer for the positive-working photoresist composition of the present invention there can be used an aqueous solution of an inorganic alkali such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate and aqueous ammonia, primary amine such as ethylamine and n-propylamine, secondary amine such as diethylamine and di-n-butylamine, tertiary amine such as triethylamine and methyldiethylamine, alcohol amine such as dimethylethanolamine and triethanolamine, quaternary ammonium salt such as tetramethylammonium hydroxide, tetraethylammonium hydroxide and choline, cyclic amine such as pyrrole and piperidine, etc. To such an aqueous solution of an alkali may be added an alcohol such as isopropyl alcohol and a surface active agent such as a nonionic type in a proper amount. The positive-working photoresist composition of the present invention may comprise a light absorber, crosslinking agent, adhesive, etc. as necessary. The light absorber is optionally used to inhibit halation from the substrate or enhance the visibility of the positive-working photoresist composition applied to a transparent substrate. Preferred examples of the light absorber employable in the present invention include commercially available light absorbers described in "Kogyoyo Shikiso no gijutsu to shijo (Techinque and market of industrial dyes)", CMC Shuppan, and "Senryou Binran (Handbook of Dyes)", Yuki Gosei Kagaku Kyokai, such as C.I. Disperse Yellow 1, 3, 4, 5, 7, 8, 13, 23, 31, 49, 50, 51, 54, 56, 60, 64, 66, 68, 79, 82, 88, 90, 93, 102, 114 and 124, C.I. Disperse Orange 1, 5, 13, 25, 29, 30, 31, 44, 57, 72 and 73, C.I. Disperse Violet 43, C.I. Disperse Blue 96, C. I. Fluorescent Brightening Agent 112, 135 and 163, C.I. Solvent Yellow 14, 16, 33 and 56, C.I. Solvent Orange 2 and 45, C.I. Solvent Red 1, 3, 8, 23, 24, 25, 27 and 49, C.I. Pigment Green 10, and C.I. Pigment Brown 2. The light absorber is blended in the positive-working photoresist composition normally in the range of not more than 100 parts by weight, preferably not more than 50 parts by weight, more preferably not more than 30 parts by weight, per 100 parts by weight of the alkali-soluble resin. The crosslinking agent is added in such an amount that the formation of positive image is not affected. The main purposes of the addition of the crosslinking agent are adjustment of sensitivity, enhancement of heat resistance and dry etching resistance, etc. Examples of the crosslinking agent employable in the present invention include compounds obtained by allowing formaldehyde to act on melamine, benzoguanamine, glycoluril, etc., alkyl-modification products thereof, epoxy compounds, aldehydes, azides, organic peroxides, and hexamethylenetetramine. These crosslinking agents may be blended in the photosensitive material in an amount of less than 10 parts by weight, preferably less than 5 parts by weight, based on 100 parts by weight of the latter. If this amount exceeds 10 parts by weight, the sensitivity of the resulting photoresist is reduced and scum (resist residue) can easily occur. The adhesive aid is used to enhance the adhesivity between the substrate and the resist, preventing the resist from being peeled off the substrate particularly at the etching step. Specific examples of the adhesive aid employable in the present invention include chlorosilanes such as chloromethylsilane, trimethylchlorosilane, dimethylvinylchlorosilane, methyldiphenylchlorosilane and chloromethyldimethylchlorosilane, alkoxysilanes such as trimethylmethoxysilane, dimethyldiethoxysilane, methyldimethoxysilane, dimethylvinylethoxysilane, diphenyldimethoxysilane and phenyltriethoxysilane, silazalanes such as hexamethyldisilazalane, N,N'-bis(trimethylsilyl)urea, dimethyltrimethylsilylamine and trimethylsilylimidazole, silanes such as vinyltrichlorosilane, γ-chloropropyltrimethoxysilane, γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane, heterocyclic compounds such as benzotriazole, benzoimidazole, indazole, imidazole, 2-mercaptobenzimidazole, 2-mercaptobenzthiazole, 2-mercaptobenzoxazole, urazole, thiouracil, mercaptoimidazole and mercaptopyrimidine, and urea or thiourea compounds such as 1,1-dimethylurea and 1,3-dimethylurea. These adhesive aids are blended normally in an amount of less than 10 parts by weight, preferably less than 5 parts by weight, per 100 parts by weight of the alkali-soluble resin. The positive-working photoresist composition of the present invention may comprise a dye and plasticizer incorporated therein as necessary. Specific examples of these additives include dyes such as methyl violet, crystal violet and malachite green, and plasticizers such as stearic acid, acetal resin, phenoxy resin and alkyd resin. The positive-working photosensitive composition thus prepared is applied to a substrate for use in the production of precision integrated circuit elements (e.g., transparent substrate such as silicon/silicon dioxide-coated substrate, glass substrate and ITO substrate) by an appropriate coating means such as spinner and coater, prebaked, exposed to light through a mask, postbaked (PEB: post exposure bake), developed, rinsed, and then dried to obtain an excellent resist. In the positive-working photoresist composition of the present invention, the area which is not irradiated with ionization radiation forms an image. In other words, a so-called positive-working pattern image is obtained. However, a method which comprises the heat treatment in an atmosphere of amine as disclosed in JP-A-63-316429 can be used, or a compounds as disclosed in JP-A-62-35350 and EP 263434A such as 2,6-di-t-butylpyridine, benzimidazole, pyridine, quinoline, acridine, lutidine, 1-methylbenzimidazole and melamineformaldehyde alkyl ether can be blended in the resin composition of the present invention, so that a so-called image reverse is conducted to effectively obtain a negative pattern. As developer for the positive-working photoresist composition of the present invention there can be used an aqueous solution of an inorganic alkali such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate and aqueous ammonia, primary amine such as ethylamine and n-propylamine, secondary amine such as diethylamine and di-n-butylamine, tertiary amine such as triethylamine and methyldiethylamine, alcohol amine such as dimethylethanolamine and triethanolamine, quaternary ammonium salt such as tetramethylammonium hydroxide, tetraethylammonium hydroxide and choline hydroxide, cyclic amine such as pyrrole and piperidine, etc. To such an aqueous solution of an alkali may be added an alcohol, surface active agent, aromatic hydroxyl group-containing compound, etc. in a proper amount. Particularly preferred among these additives is tetramethylammonium hydroxide. The present invention will be further described hereinafter. The term "%" as used herein is meant to indicate % by weight unless otherwise specified. (1) Synthesis of Compound (Ib-1) 29.6 g of 1,1-bis(3'-methyl-4'-hydroxyphenyl) cyclohexane, 91.15 g of a 25 % aqueous solution of tetrahydroxyammonium hydroxide, and 600 mℓ of distilled water were charged into a four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping apparatus. The mixture was then heated to a temperature of 50 °C with stirring to dissolve 1,1-bis(3'-methyl-4'-hydroxyphenyl) cyclohexane. To the mixture solution was then added dropwise 24.3 g of a 37 % aqueous solution of formalin in 10 minutes. The reaction mixture was then heated with stirring for 14 hours. The resulting reaction mixture was then diluted with 400 mℓ of distilled water. To the reaction mixture were then added dropwise 15.0 g of acetic acid and 200 mℓ of distilled water in 30 minutes. The white powder thus precipitated was then recovered by filtration to obtain 33 g of Compound a . 17.8 g of Compound a thus obtained, 108.1 g of o-cresol, and 100 mℓ of methanol were charged into the same reaction apparatus as used above. The mixture was heated to a temperature of 40 °C with stirring to dissolve Compound a . To the solution was then added dropwise 0.5 g of sulfuric acid. The mixture was then heated with stirring for 10 hours. The resulting reaction mixture was poured into 1 ℓ of distilled water. The resulting brown solid was then purified by column chromatography to obtain 12.0 g of the desired material (Ib-1) in the form of a light yellow solid. The purity of the desired material thus obtained was 96 % as determined by GPC with polystyrene as a standard. (2) Synthesis of Compound (Ib-2) Compound (Ib-2) was synthesized in the same manner as in Synthesis of Compound (Ib-1) described above except that 122.17 g of 2,5-dimethylphenol was used instead of o-cresol. The purity of the desired material thus obtained was 97 %. (3) Synthesis of Compound (Ib-9) 29.6 g of 1,1-bis(3'-methyl-4'-hydroxyphenyl) cyclohexane, 130.2 g of 3-hydroxy-α-methylstyrene, and 50 mℓ of methanol were charged into a three-necked flask equipped with a stirrer, a condenser, and a thermometer to make a uniform solution. To the solution was then added 0.3 g of concentrated hydrochloric acid. The mixture was then heated to a temperature of 50 °C with stirring for 8 hours. The resulting reaction mixture was then poured into 1 ℓ of distilled water. The resulting brown solid was then purified by column chromatography to obtain 13.2 g of the desired material (Ib-9) in the form of a light yellow solid. The purity of the desired material thus obtained was 98 % as determined by GPC with polystyrene as a standard. (4) Synthesis of Photosensitive Material a 53.7 g of Compound (Ib-1), 53.7 g of 1,2-naphthoquinonediazide-5-sulfonyl chloride, and 800 mℓ of acetone were charged into a three-necked flask to make a uniform solution. To the solution was then gradually added dropwise 21.2 g of triethylamine. The reaction mixture was then allowed to undergo reaction at a temperature of 25 °C for 3 hours. The reaction mixture solution was then poured into 3 ℓ of a 1 % aqueous solution of hydrochloric acid. The resulting precipitate was recovered by filtration, washed with water, and then dried at a temperature of 40 °C to obtain 90.2 g of a 1,2-naphthoquinonediazide-5-sulfonic esterification product of Compound (Ib-1) (Photosensitive Material a ). The HPLC of Photosensitive Material a with ultraviolet ray at 254 nm showed that the pattern area of diester compound accounts for 60 % of all the pattern area and the pattern area of complete ester (tetraester) compound accounts for 3 % of all the pattern area. (5) Synthesis of Photosensitive Material b 53.7 g of Compound (Ib-1), 53.7 g of 1,2-naphthoquinonediazide-5-sulfonyl chloride, and 800 mℓ of acetone were charged into a three-necked flask to make a uniform solution. To the solution was then gradually added dropwise 20.8 g of N-methylpiperidine. The reaction mixture was then allowed to undergo reaction at a temperature of 25 °C for 3 hours. The reaction mixture solution was then poured into 3 ℓ of a 1 % aqueous solution of hydrochloric acid. The resulting precipitate was recovered by filtration, washed with water, and then dried at a temperature of 40 °C to obtain 91.4 g of a 1,2-naphthoquinonediazide-5-sulfonic esterification product of Compound (Ib-1) (Photosensitive Material b ). The HPLC of Photosensitive Material b with ultraviolet ray at 254 nm showed that the pattern area of diester compound accounts for 65 % of all the pattern area and the pattern area of complete ester (tetraester) compound accounts for 3 % of all the pattern area. (6) Synthesis of Photosensitive Material c 53.7 g of Compound (Ib-1), 53.7 g of 1,2-naphthoquinonediazide-5-sulfonyl chloride, and 1 ℓ of chloroform were charged into a three-necked flask to make a uniform solution. To the solution was then gradually added dropwise 20.8 g of N-methylpiperidine. The reaction mixture was then allowed to undergo reaction at a temperature of 25 °C for 3 hours. The reaction mixture solution was concentrated, dissolved in 900 mℓ of 1,4-dioxan, and then poured into 3 ℓ of a 1 % aqueous solution of hydrochloric acid. The resulting precipitate was recovered by filtration, washed with water, and then dried at a temperature of 40 °C to obtain 85.7 g of a 1,2-naphthoquinonediazide-5-sulfonic esterification product of Compound (Ib-1) (Photosensitive Material c ). The HPLC of Photosensitive Material c with ultraviolet ray at 254 nm showed that the pattern area of diester compound accounts for 70 % of all the pattern area and the pattern area of complete ester (tetraester) compound accounts for 2 % of all the pattern area. (7) Synthesis of Photosensitive Material d 56.5 g of Compound (Ib-2), 53.7 g of 1,2-naphthoquinonediazide-5-sulfonyl chloride, and 800 mℓ of 1,4-dioxan were charged into a three-necked flask to make a uniform solution. To the solution was then gradually added dropwise 20.8 g of N-methylpiperidine. The reaction mixture was then allowed to undergo reaction at a temperature of 25 °C for 3 hours. The reaction mixture solution was then poured into 3 ℓ of a 1 % aqueous solution of hydrochloric acid. The resulting precipitate was recovered by filtration, washed with water, and then dried at a temperature of 40 °C to obtain 92.7 g of a 1,2-naphthoquinonediazide-5-sulfonic esterification product of Compound (Ib-2) (Photosensitive Material d ). The HPLC of Photosensitive Material d with ultraviolet ray at 254 nm showed that the pattern area of diester compound accounts for 55 % of all the pattern area and the pattern area of complete ester (tetraester) compound accounts for 5 % of all the pattern area. (8) Synthesis of Photosensitive Material e 56.6 g of Compound (Ib-9), 53.7 g of 1,2-naphthoquinonediazide-5-sulfonyl chloride, and 800 mℓ of acetone were charged into a three-necked flask to make a uniform solution. To the solution was then gradually added dropwise 20.8 g of N-methylpiperidine. The reaction mixture was then allowed to undergo reaction at a temperature of 25 °C for 3 hours. The reaction mixture solution was then poured into 3 ℓ of a 1 % aqueous solution of hydrochloric acid. The resulting precipitate was recovered by filtration, washed with water, and then dried at a temperature of 40 °C to obtain 92.8 g of a 1,2-naphthoquinonediazide-5-sulfonic esterification product of Compound (Ib-9) (Photosensitive Material e ). The HPLC of Photosensitive Material e with ultraviolet ray at 254 nm showed that the pattern area of diester compound accounts for 66 % of all the pattern area and the pattern area of complete ester (tetraester) compound accounts for 4 % of all the pattern area. (9) Synthesis of Photosensitive Material f 56.5 g of Compound (Ib-2), 53.7 g of 1,2-naphthoquinonediazide-5-sulfonyl chloride, and 800 mℓ of acetone were charged into a three-necked flask to make a uniform solution. To the solution was then gradually added dropwise 21.2 g of triethylamine. The reaction mixture was then allowed to undergo reaction at a temperature of 25 °C for 3 hours. The reaction mixture solution was then poured into 3 ℓ of a 1 % aqueous solution of hydrochloric acid. The resulting precipitate was recovered by filtration, washed with water, and then dried at a temperature of 40 °C to obtain 92.7 g of a 1,2-naphthoquinonediazide-5-sulfonic esterification product of Compound (Ib-2) (Photosensitive Material f ). The HPLC of Photosensitive Material f with ultraviolet ray at 254 nm showed that the pattern area of diester compound accounts for 45 % of all the pattern area and the pattern area of complete ester (tetraester) compound accounts for 6 % of all the pattern area. (10) Synthesis of Photosensitive Material g 53.7 g of Compound (Ib-1), 61.8 g of 1,2-naphthoquinonediazide-5-sulfonyl chloride, and 1,000 mℓ of acetone were charged into a three-necked flask to make a uniform solution. To the solution was then gradually added dropwise 24.4 g of triethylamine. The reaction mixture was then allowed to undergo reaction at a temperature of 25 °C for 3 hours. The reaction mixture solution was then poured into 3.5 ℓ of a 1 % aqueous solution of hydrochloric acid. The resulting precipitate was recovered by filtration, washed with water, and then dried at a temperature of 40 °C to obtain 96.5 g of a 1,2-naphthoquinonediazide-5-sulfonic esterification product of Compound (Ib-1) (Photosensitive Material g ). The HPLC of Photosensitive Material g with ultraviolet ray at 254 nm showed that the pattern area of diester compound accounts for 33 % of all the pattern area and the pattern area of complete ester (tetraester) compound accounts for 15 % of all the pattern area. (11) Synthesis of Photosensitive Material h 53.7 g of Compound (Ib-1), 94.0 g of 1,2-naphthoquinonediazide-5-sulfonyl chloride, and 1,200 mℓ of acetone were charged into a three-necked flask to make a uniform solution. To the solution was then gradually added dropwise 37.2 g of triethylamine. The reaction mixture was then allowed to undergo reaction at a temperature of 25 °C for 3 hours. The reaction mixture solution was then poured into 4 ℓ of a 1 % aqueous solution of hydrochloric acid. The resulting precipitate was recovered by filtration, washed with water, and then dried at a temperature of 40 °C to obtain 121.6 g of a 1,2-naphthoquinonediazide-5-sulfonic esterification product of Compound (Ib-1) (Photosensitive Material h ). The HPLC of Photosensitive Material h with ultraviolet ray at 254 nm showed that the pattern area of diester compound accounts for 5 % of all the pattern area and the pattern area of complete ester (tetraester) compound accounts for 60 % of all the pattern area. (12) Synthesis of Photosensitive Material i 24.4 g of Compound (III) having the following structural formula, 53.7 g of 1,2-naphthoquinonediazide-5-sulfonyl chloride, and 800 mℓ of acetone were charged into a three-necked flask to make a uniform solution. To the solution was then gradually added dropwise 21.2 g of triethylamine. The reaction mixture was then allowed to undergo reaction at a temperature of 25 °C for 3 hours. The reaction mixture solution was then poured into 2,500 mℓ of a 1 % aqueous solution of hydrochloric acid. The resulting precipitate was recovered by filtration, washed with water, and then dried at a temperature of 40 °C to obtain 63.8 g of a 1,2-naphthoquinonediazide-5-sulfonic esterification product of Compound (III) (Photosensitive Material i ). The HPLC of Photosensitive Material i with ultraviolet ray at 254 nm showed that the pattern area of diester compound accounts for 80 % of all the pattern area and the pattern area of complete ester (triester) compound accounts for 8 % of all the pattern area. Compound (III) (13) Synthesis of Photosensitive Material j 30.0 g of Compound (IV) having the following structural formula, 53.7 g of 1,2-naphthoquinonediazide-5-sulfonyl chloride, and 800 mℓ of chloroform were charged into a three-necked flask to make a uniform solution. To the solution was then gradually added dropwise 21.2 g of triethylamine. The reaction mixture was then allowed to undergo reaction at a temperature of 25 °C for 3 hours. The reaction mixture solution was concentrated, dissolved in 900 mℓ of 1,4-dioxan, and then poured into 2,500 mℓ of a 1 % aqueous solution of hydrochloric acid. The resulting precipitate was recovered by filtration, washed with water, and then dried at a temperature of 40 °C to obtain 68.8 g of a 1,2-naphthoquinonediazide-5-sulfonic esterification product of Compound (IV) (Photosensitive Material j ). The HPLC of Photosensitive Material j with ultraviolet ray at 254 nm showed that the pattern area of diester compound accounts for 89 % of all the pattern area and the pattern area of complete ester (tetraester) compound accounts for 4 % of all the pattern area. Compound (IV) (14) Synthesis of Photosensitive Material k 35.2 g of Compound (V) having the following structural formula, 107.5 g of 1,2-naphthoquinonediazide-5-sulfonyl chloride, and 1,200 mℓ of acetone were charged into a three-necked flask to make a uniform solution. To the solution was then gradually added dropwise 42.5 g of triethylamine. The reaction mixture was then allowed to undergo reaction at a temperature of 25 °C for 3 hours. The reaction mixture solution was then poured into 4,000 mℓ of a 1 % aqueous solution of hydrochloric acid. The resulting precipitate was recovered by filtration, washed with water, and then dried at a temperature of 40 °C to obtain 68.8 g of a 1,2-naphthoquinonediazide-5-sulfonic esterification product of Compound (V) (Photosensitive Material k ). The HPLC of Photosensitive Material k with ultraviolet ray at 254 nm showed that the pattern area of diester compound accounts for 15 % of all the pattern area and the pattern area of complete ester (pentaester) compound accounts for 5 % of all the pattern area. Compound (V) (15) Synthesis of Photosensitive Material l 65.1 g of Compound (VI) having the following structural formula, 107.5 g of 1,2-naphthoquinonediazide-5-sulfonyl chloride, and 1,500 mℓ of acetone were charged into a three-necked flask to make a uniform solution. To the solution was then gradually added dropwise 42.5 g of triethylamine. The reaction mixture was then allowed to undergo reaction at a temperature of 25 °C for 3 hours. The reaction mixture solution was then poured into 4,000 mℓ of a 1 % aqueous solution of hydrochloric acid. The resulting precipitate was recovered by filtration, washed with water, and then dried at a temperature of 40 °C to obtain 142.1 g of a 1,2-naphthoquinonediazide-5-sulfonic esterification product of Compound (VI) (Photosensitive Material l ). The HPLC of Photosensitive Material l with ultraviolet ray at 254 nm showed that the pattern area of diester compound accounts for 20 % of all the pattern area and the pattern area of complete ester (hexaester) compound accounts for 5 % of all the pattern area. Compound (VI) (16) Synthesis of Novolak Resin A 45 g of m-cresol, 55 g of p-cresol, 49 g of a 37 % aqueous solution of formalin, and 0.13 g of oxalic acid were charged into a three-necked flask. The reaction mixture was then heated with stirring to a temperature of 100 °C where it was then allowed to undergo reaction for 15 hours. The reaction system was then heated to a temperature of 200 °C where it was then gradually evacuated to 5 mmHg to remove water, unreacted monomers, formaldehyde, oxalic acid, etc. therefrom. The alkali-soluble novolak resin thus melted was allowed to cool to room temperature and then recovered. The novolak resin A thus obtained had a weight-average molecular weight of 8,100 (reduced to polystyrene) and a dispersion degree of 6.30. (17) Synthesis of Novolak Resin B 50 g of m-cresol, 25 g of p-cresol, 28 g of 2,5-xylenol, 53 g of a 37 % aqueous solution of formalin, and 0.15 g of oxalic acid were charged into a three-necked flask. The reaction mixture was then heated with stirring to a temperature of 100 °C where it was then allowed to undergo reaction for 14 hours. The reaction system was then heated to a temperature of 200 °C where it was then gradually evacuated to 1 mmHg to remove water, unreacted monomers, formaldehyde, oxalic acid, etc. therefrom. The novolak resin thus melted was allowed to cool to room temperature and then recovered. The novolak resin thus obtained had a weight-average molecular weight of 4,800 (reduced to polystyrene). 20 g of the novolak resin was then completely dissolved in 60 g of methanol. To the resin solution was then gradually added 30 g of water with stirring to precipitate the resin component. The upper phase was removed by decantation. The resin component thus precipitated was recovered, heated to a temperature of 40 °C, and then dried under reduced pressure for 24 hours to obtain an alkali-soluble novolak resin B. The novolak resin thus obtained had a weight-average molecular weight of 9,960 (reduced to polystyrene) and a dispersion degree of 3.50. The novolak resin also exhibited monomer, dimer and trimer contents of 0 %, 2.3 % and 3.5 %, respectively, showing that the low molecular components had been removed in an amount of 43 % by the fractional reprecipitation process. (18) Synthesis of Novolak Resin C 60 g of m-cresol, 20 g of p-cresol, 25 g of 2,3,5-trimethylphenol, 56 g of a 37 % aqueous solution of formalin, and 0.16 g of oxalic acid were charged into a three-necked flask. The reaction mixture was then heated with stirring to a temperature of 100 °C where it was then allowed to undergo reaction for 16 hours. The reaction system was then heated to a temperature of 200 °C where it was then gradually evacuated to 1 mmHg to remove water, unreacted monomers, formaldehyde, oxalic acid, etc. therefrom. The novolak resin thus melted was allowed to cool to room temperature and then recovered. The novolak resin thus obtained had a weight-average molecular weight of 3,800 (reduced to polystyrene). 20 g of the novolak resin was then completely dissolved in 60 g of acetone. To the resin solution was then gradually added 60 g of hexane with stirring. The mixture was then allowed to stand for 2 hours. The upper phase was removed by decantation. The resin component thus precipitated was recovered, heated to a temperature of 40 °C, and then dried under reduced pressure for 24 hours to obtain an alkali-soluble novolak resin C. The novolak resin thus obtained had a weight-average molecular weight of 8,300 (reduced to polystyrene) and a dispersion degree of 3.20. The novolak resin also exhibited monomer, dimer and trimer contents of 0 %, 2.1 % and 3.0 %, respectively, showing that the low molecular components had been removed in an amount of 56 % by the fractional reprecipitation process. (19) Synthesis of Novolak Resin D 30 g of p-cresol, 14 g of o-cresol, 50 g of 2,3-dimethylphenol, 20 g of 2,3,5-trimethylphenol, and 4.9 g of 2,6-dimethylphenol were mixed with 50 g of diethylene glycol monomethyl ether. The mixture was then charged into a three-necked flask equipped with a stirrer, a condenser and a thermometer. To the reaction mixture was then added 85 g of a 37 % aqueous solution of formalin. The reaction mixture was then stirred over a 110 °C oil bath. When the internal temperature of the reaction system reached 90 °C, 6.3 g of oxalic acid dihydrate was added to the reaction system. The temperature of the oil bath was then raised to 130 °C where the reaction system continued to undergo reaction for 18 hours. The condenser was then removed. The reaction system was then distilled at a temperature of 200 °C under reduced pressure to remove unreacted monomers therefrom. The novolak resin thus obtained exhibited Mw of 3,280 and a dispersion degree of 2.75. (20) Preparation and evaluation of positive-working photoresist composition The photosensitive materials, the novolak resins, solvents, and optionally water-insoluble alkali-soluble compounds were mixed in proportions as set forth in Table 1, respectively, to make uniform solutions. These solutions were each filtered through a teflon microfilter having a pore diameter of 0.10 µm to prepare photoresist compositions. These photoresist compositions were each applied to a silicon wafer by means of a spinner at different numbers of rotation, respectively, and then dried at a temperature of 90 °C over a vacuum suction hot plate for 60 seconds to obtain resist films having a thickness of 0.97 µm and 1.02 µm. These films were each exposed to light from a reduction projection exposing apparatus (NSR-2005i9C available from Nikon Corporation), postbaked at a temperature of 110 °C for 60 seconds, developed with a 2.38 % aqueous solution of tetramethylammonium hydroxide for 1 minute, washed with water for 30 seconds, and then dried. The resist patterns thus obtained on the silicon wafers were then observed under a scanning electron microscope to evaluate the resist. The results are set forth in Table 2. Sensitivity was defined by a reciprocal of an exposure necessary for reproducing a mask pattern of 0.60 µm and expressed by a value relative to that of Comparative Example 1 with a resist film thicknes of 1.02 µm, which was set at 1.0. Resolving power represents a critical resolving power in an exposure necessary for reproducing a mask pattern of 0.60 µm. Heat resistance was represented by the highest allowable temperature at which the silicon wafer on which a resist pattern has been formed can be baked over a hot plate for 4 minutes without causing the pattern to be deformed. Resist shape was represented by the angle () made by the resist wall and the surface of the silicon wafer on a section of 0.50-µm thick resist pattern. Development Residue was evaluated by observing the resist patterns obtained on the silicon wafers under a scanning electron microscope. A: No residue is observed. B: Residue is observed. For the evaluation of storage stability, the positive-working photoresist composition solution was allowed to stand at room temperature for 6 months. The presence of precipitates in the solution was then examined. In Table 2, "A" indicates the absence of precipitates while "B" indicates the presence of precipitates. The results are set forth in Table 2. The positive-working photoresist comprising the photosensitive material of the present invention exhibits excellent sensitivity and resolving power as well as little dependence of properties on film thickness, little development residue and excellent storage stability.

Claims: A positive-working photoresist composition, comprising an alkali-soluble resin and a 1,2-naphthoquinonediazide-5-(and/or -4-)sulfonic ester of a water-insoluble alkali-soluble low molecular compound represented by formula (Ib) obtained by the esterification reaction of the water-insoluble alkali-soluble low molecular compound represented by formula (Ib) with 1,2-naphthoquinonediazide-5-(and/or -4-)sulfonyl chloride, wherein the high-performance liquid chromatography of said ester with an ultraviolet ray at 254 nm shows that the patterns corresponding to the diester components and complete ester component of said ester are not less than 40 % and less than 10 % of the total pattern area of said ester, respectively: wherein R 1b to R 10b may be the same or different and each represents a hydrogen atom, a halogen atom selected from a chlorine atom, a bromine atom and an iodine atom, a C 1-4 alkyl group, a cyclic alkyl group selected from a cyclopentyl group and a cyclohexyl group, an aryl group selected from a phenyl group, a toluyl group, a xylyl group and a cumenyl group, a C 1-4 alkoxy group, an acyl group selected from a formyl group, an acetyl group and a benzoyl group, an alkenyl group selected from a vinyl group, a propenyl group and an allyl group, or a hydroxyl group, with the proviso that at least one of R 1b to R 5b and at least one of R 6b to R 10b each is a hydroxyl group; and R 11b to R 14b may be the same or different and each represents a hydrogen atom or a C 1-4 alkyl group. The positive-working photoresist composition according to Claim 1, wherein said water-insoluble alkali-soluble low molecular compound is represented by formula (IIb): wherein R 15b 's may be the same or different and each represent a hydrogen atom or a methyl group. The positive-working photoresist composition according to Claim 1, wherein said ester is a compound obtained by the esterification reaction using N-methylpiperidine or N-methylpyrrolidine.

Inventors: AOAI TOSHIAKI, KAWABE YASUMASA, SAKAGUCHI SHINJI, SATO KENICHIRO, AOAI, TOSHIAKI, KAWABE, YASUMASA, SAKAGUCHI, SHINJI, SATO, KENICHIRO, AOAI, TOSHIAKI, C/O FUJI PHOTO FILM CO., LTD., KAWABE, YASUMASA, C/O FUJI PHOTO FILM CO., LTD., SAKAGUCHI, SHINJI, C/O FUJI PHOTO FILM CO., LTD., SATO, KENICHIRO, C/O FUJI PHOTO FILM CO., LTD.
Applicants: FUJI PHOTO FILM CO LTD, FUJI PHOTO FILM CO., LTD.
Application year: 1994
Main classification: G03F7
IPC codes: G03F7